The snooze button is one of life's little luxuries, and it's easy to kid yourself into thinking that all you need is an extra ten, twenty—hell, let's make it thirty—minutes in the sack.

But if you're lying there snoozing, you're lying to yourself. At best, it's a psychological crutch. At worst, it's throwing off your brain chemistry for the day. And it's certainly not helping you get any real rest.

It's not pure bliss to have a body pumped full of serotonin, though. Through the course of the night, the chemicals dumped into your bloodstream change. The average adult needs 7-9 hours sleep a night, and while the exact amount varies person-to-person, your body knows when you've had enough, and pumps out dopamine to to suppress feelings of sleepiness and prepare you to wake. As you hit the snooze button and return to sleep and re-start that dopamine drip, your body become a chemical cocktail shaker, as neurotransmitters rattle around providing conflicting influences. The snooze might release some feel-good chemicals, but ultimately it's pulling your body in different directions. That chemical confusion leaves you feeling disoriented, and makes it difficult to get going.

Short, but not so sweet

You probably know that sleep occurs in cycles—a complex series of sleep-types with different neurological features and benefits. The two most important are rapid eye movement (REM) and deep sleep. The first lets your brain sift through the pervious day's activities, while the second provides the pure rest your body requires to function. The two come and go during the night, and the duration of each stage varies from person to person. But we all experience more deep sleep early in the night, and more REM sleep before natural awakening, triggered by shifting chemical balances.

During the hour or two before you wake, then, you primarily have REM sleep. You dream a lot during this period, and consolidate recent memories. Weirdly, this means that your body does most of the processing of the preceding day's events just before you wake naturally. The earlier you interrupt that process—by, say, setting an alarm earlier than you need so you can snooze away for a half hour—the less time you give yourself to process those experiences. Research shows that cutting into REM sleep like that can blunt your mental function during the day.

A fundamental belief about the snooze button is that the short snatches of sleep still help the body rest. Studies into sleep fragmentation suggest otherwise—sleep which is interrupted every minute or every ten can lead to "sleepiness-related daytime impairment" when compared to the equivalent amount of uninterrupted sleep. In other words, there is less value in snooze sleep and, if too much of your bed time is spent snoozing, you can expect impairments in your memory, reaction time, comprehension and attention.

What you can do

If you're waking up tired every morning, it's time to face facts: You're not getting enough sleep, and no amount of snoozing is going to fix it. The best advice is to keep going to bed earlier until you naturally wake up just before your alarm—then you know you're getting all the sleep your body needs. But who are we kidding? However nice it would be live without an alarm clock, it probably isn't gonna happen. If the temptation of the snooze button is too much, you can at least try and minimize the negative effects it has.

So, take a cue from the sleep fragmentation experts, who suggest that the optimal nap length is around 20 minutes. Less than that, and you gain little benefit. But much more, and you risk falling into deep sleep, which will make the wake-up more difficult. Squeezing in a nap isn't ideal, but it's less disruptive than a 5- or 10-minute morning snooze time.

Of course, alarm clock technology continues to advance. On Android devices and iPhones, you can now set a specific interval of snooze. So if you really can't resist, dial it up to a luxurious 20 minutes. It just might minimize the damage.